A Treatise On The Principles And Practice Of Dock Engineering

CANADA LOCK, LIVERPOOL. 259 cement, with a large proportion of sandstone and granite burrs thrown in. The thickness of the new floor averages 7 feet, and the upper surface is coated with a 6-inch layer of granolithic conerete. A transverse section (fig. 184) shows the floor to be flat for a width of 80 feet and connected with the sides by circular curves of 10 feet radius. The side walls were under- pinned with conerete in bays of from 12 to 15 feet in length. A gas- and water-pipe culvert, 5 feet in diameter, is arranged below the floor level. The stone work comprises copings, hollow quoins, culvert quoins, caisson quoins, gate silis, caisson sills, culvert sills and heads—all of Scotch granite, with square quoins of sandstone. The work was carried out in the following manner : —The outer sill in the tidal basin was reconstructed during low water of spring tides in small sections, within a piled dam, which was pumped out on each occasion. On the completion of the work a stank of conerete blocks was built across it Hiqh Water - Ordinary ^ Feeqo Fides tOO’- 0 Floor 'S. of CAomber Boielder Clay Fig. 184.— Section of Canada Lock, Liverpool, as deepened. between the side walls of the lock, and carried up above the level of high water. These blooks were of uniform size, 11 feet 3 inches by 3 feet by 3 feet, each containing about 100 cubic feet. They were made in wooden moulds at least a fortnight before using, and were deposited by means of overhead steam travellers, double tracks for which, 64 feet wide, ran the whole length of the lock. To ensure watertightness, the blocks were bedded in cement mortar. At the same time, to facilitate their later removal, a sheet of common brown paper was interposed between the block and the mortar. The plan answered admirably, the blocks being perfectly bedded without the undesired adhesion. It is needless to add that the stability of the dam in no way depended upon the tenacity of the joints. The inner end of the lock was enclosed by a cofferdam, constructed of piles and tiniber framing and filled with clay puddle. A section of the dam is illustrated in fig. 66 (p. 107). When the dams were completed no difficulty was experienced in bringing the work to a rapid and successful conclusion. Three chain pumps with wooden blades, 2 feet 6 inches by